class NodeRevisionRevertForm

class NodeRevisionRevertForm extends ConfirmFormBase {
  
  /**
   * The node revision.
   *
   * @var \Drupal\node\NodeInterface
   */
  protected $revision;
  
  /**
   * The node storage.
   *
   * @var \Drupal\node\NodeStorageInterface
   */
  protected $nodeStorage;
  
  /**
   * The date formatter service.
   *
   * @var \Drupal\Core\Datetime\DateFormatterInterface
   */
  protected $dateFormatter;
  
  /**
   * The time service.
   *
   * @var \Drupal\Component\Datetime\TimeInterface
   */
  protected $time;
  
  /**
   * Constructs a new NodeRevisionRevertForm.
   *
   * @param \Drupal\Core\Entity\EntityStorageInterface $node_storage
   *   The node storage.
   * @param \Drupal\Core\Datetime\DateFormatterInterface $date_formatter
   *   The date formatter service.
   * @param \Drupal\Component\Datetime\TimeInterface $time
   *   The time service.
   */
  public function __construct(EntityStorageInterface $node_storage, DateFormatterInterface $date_formatter, TimeInterface $time) {
    $this->nodeStorage = $node_storage;
    $this->dateFormatter = $date_formatter;
    $this->time = $time;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container->get('entity_type.manager')
      ->getStorage('node'), $container->get('date.formatter'), $container->get('datetime.time'));
  }
  
  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'node_revision_revert_confirm';
  }
  
  /**
   * {@inheritdoc}
   */
  public function getQuestion() {
    return $this->t('Are you sure you want to revert to the revision from %revision-date?', [
      '%revision-date' => $this->dateFormatter
        ->format($this->revision
        ->getRevisionCreationTime()),
    ]);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getCancelUrl() {
    return new Url('entity.node.version_history', [
      'node' => $this->revision
        ->id(),
    ]);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getConfirmText() {
    return $this->t('Revert');
  }
  
  /**
   * {@inheritdoc}
   */
  public function getDescription() {
    return '';
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state, ?NodeInterface $node_revision = NULL) {
    $this->revision = $node_revision;
    $form = parent::buildForm($form, $form_state);
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    // The revision timestamp will be updated when the revision is saved. Keep
    // the original one for the confirmation message.
    $original_revision_timestamp = $this->revision
      ->getRevisionCreationTime();
    $this->revision = $this->prepareRevertedRevision($this->revision, $form_state);
    $this->revision->revision_log = $this->t('Copy of the revision from %date.', [
      '%date' => $this->dateFormatter
        ->format($original_revision_timestamp),
    ]);
    $this->revision
      ->setRevisionUserId($this->currentUser()
      ->id());
    $this->revision
      ->setRevisionCreationTime($this->time
      ->getRequestTime());
    $this->revision
      ->setChangedTime($this->time
      ->getRequestTime());
    $this->revision
      ->save();
    $this->logger('content')
      ->info('@type: reverted %title revision %revision.', [
      '@type' => $this->revision
        ->bundle(),
      '%title' => $this->revision
        ->label(),
      '%revision' => $this->revision
        ->getRevisionId(),
    ]);
    $this->messenger()
      ->addStatus($this->t('@type %title has been reverted to the revision from %revision-date.', [
      '@type' => node_get_type_label($this->revision),
      '%title' => $this->revision
        ->label(),
      '%revision-date' => $this->dateFormatter
        ->format($original_revision_timestamp),
    ]));
    $form_state->setRedirect('entity.node.version_history', [
      'node' => $this->revision
        ->id(),
    ]);
  }
  
  /**
   * Prepares a revision to be reverted.
   *
   * @param \Drupal\node\NodeInterface $revision
   *   The revision to be reverted.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @return \Drupal\node\NodeInterface
   *   The prepared revision ready to be stored.
   */
  protected function prepareRevertedRevision(NodeInterface $revision, FormStateInterface $form_state) {
    $revision->setNewRevision();
    $revision->isDefaultRevision(TRUE);
    return $revision;
  }

}